I think it needs to be pointed out that when Sony sells assets they are not in fact toxic. The only reason that Sony is able to sell these assets in the first place. Is the simple fact that they are indeed profitable. They actually make Sony money, but not necessarily the amount of money that Sony needs here and now. People don't buy businesses that are losing money. In a very real sense Sony is actually running out of stuff to sell as is, and as such Sony will have to start either selling assets below their appraised value, because they cannot be sold as is, or Sony is going to have to do the unthinkable. Namely going after the divisions that actually generate the greatest profits in the company.
I seriously doubt that the investment community would tolerate the latter. They might stomach Sony selling a big factory at a ten million dollar loss. They would go nuclear if Sony started to go after the heart. Anyway selling off assets in the past was a stop gap that never really worked. They as in Sony always ended up coming up short year after year. No matter how much of their own stuff they had sold off.
When Sony gets down to assets that cannot be sold as is, or are already outright toxic. Then they are going to go into a diminishing returns scenario. Where they have to sell more and more to get the same out. While the act of selling at a loss will actually drive down the total value of the company at a ever increasing rate. I think that is part of what the investment agency is relating to in all of this. The fact that Sony is just about drawing dead. There really aren't a lot of ways for Sony to get off the track it is on, and most of those revolve around Sony coming up with a surprise hit.